Converting machinery falls into two categories, winders and unwinders. In a winder, a high-speed incoming web is wound onto a roll until the roll is filled. During winding, a core for winding a new roll is brought into position to continue winding the incoming web. The problem then is to transfer the winding from the completed roll to the new core by terminating winding on the original roll, and beginning winding on the core for the new roll. Originally the transfer was made by stopping the web, cutting the web, and affixing the leading edge of the web to the core using, for example a strip of adhesive tape. Upon completion of this transfer, the web was restarted. This procedure is called zero-speed transfer.
In an unwinder, a roll feeds an outgoing web. During unwinding, a filled roll is brought into position to assume the feeding role as the original roll is depleted. The problem of transfer from one roll to the next is the same as for the winder discussed above.
Filled rolls of, for example, newsprint, are large and heavy. Some such rolls weigh several tons. Stopping and starting heavy rolls for zero-speed splicing imposes a heavy time delay. This time delay has a serious impact on productivity.
In the case where the process feeding the winder, or the process receiving web from the unwinder, is a continuous process, a problem arises in interfacing a start-stop winding/unwinding process with a continuous feeding or receiving process.
The prior art discloses techniques for on-the-fly joining of the end of a web feeding a building roll in a winder, or being fed from a feeding roll in an unwinder. In an example of a web being wound on a succession of rolls, a core for a new roll is moved into position adjacent the moving web. A strip of adhesive tape is disposed along the core. The core is rotated up to a speed that is synchronous with the moving web. At the appropriate time, a knife is fired into the moving web to sever it. A bump roll is triggered to press the severed leading edge of the web into contact with the adhesive tape on the rotating core. Winding then continues, unabated, on the core. Since the peripheral speeds of the core and the incoming web are equal, the transfer takes place without disruption in web flow.
In an unwinder, the leading edge of the replacement roll receives adhesive tape. The replacement roll is accelerated to match its peripheral speed with that of the web passing thereby. At the appropriate time, a knife is fired to sever the web from the depleting roll, and a bump roll is fired to press the trailing edge of the severed web onto the adhesive tape on the leading edge of the replacement roll. As in the case of the winder discussed above, the supply of web continues unabated from the replacement roll.
A different problem is evidenced when it is desired to splice a two-ply web. As will be seen from the detailed description of the present invention, it is not sufficient to merely cut and splice the leading edge of the web from the replacement to the trailing end of the web from the depleting roll. A two-ply web may include, for example, a protective liner which carries a web of interest. For proper joining, the leading edge of the incoming liner must be spliced to the trailing edge of the outgoing liner, and the leading edge of the web of interest must be spliced to the trailing edge of its counterpart on the outgoing material. The inventors are unaware of any system which permits splicing a two-ply web on the fly. Instead, the prior art requires that the web be stopped for a zero-speed manual splice, with the disadvantages of zero-speed splicing discussed above.
Accordingly, it is an object of the invention to provide a splicing technique which overcomes the drawbacks of the prior art.
It is a further object of the invention to provide a splicing technique which permits the splicing of a two-ply web on the fly.
Briefly stated, the present invention provides a splicing apparatus and method in which the severed trailing edge of a two-ply web is spliced to a leading edge of a replacement web on a replacement roll in a two-part operation which permits on-the-fly splicing. The upper ply of the replacement web is trimmed back to reveal a strip of the lower ply. A splice tape is placed under the edge of the lower ply with a portion of the splice tape exposed. A splice roll is prepared with a splice sheet having first and second adhesive strips spaced apart on it. The replacement roll and splice roll are accelerated to synchronize their peripheral speeds with the web speed. The rotational phases of the replacement roll and splice roll are coordinated. A bump roll is triggered to urge the web against the replacement roll. A cut-off knife is triggered to sever the web. The bump roll and cut-off knife trigger are timed so that the trailing edge of the severed web falls into contact with the exposed portion of the splice tape. This splices the lower plies together. The splice roll is urged into contact with the web at a rotational phase and a timing effective to adhere the first adhesive strip to the upper ply of the web downstream of the splice and the second adhesive strip to the upper ply upstream of the splice with the splice sheet bridging the gap between the first and second adhesive strips. The completed splice permits independent subsequent handling, separation, etc. of the first and second plies.
According to an embodiment of the invention, there is provided a web splicer for on-the-fly splicing of a leading edge of a replacement web with a web comprising: the replacement web being wound on a replacement roll movable into a position spaced from a first surface of the web, a bump roll at a second surface of the web, a cut-off knife, means for matching a speed of a peripheral surface of the replacement roll with a speed of the web, means for urging the bump roll into contact with the web, and for severing the web, at a timing whereby urging the web into contact with the replacement roll affixes a splice tape at a trailing end of the web, where severed, injoining contact with the first surface of a leading edge of the replacement web, whereby a first surface of the web is spliced to a first surface of the replacement web, a splice roll, the splice roll being adapted for the attachment thereto of a splice sheet with first and second spacedapart adhesive strips affixed thereto, means for urging the splice roll into contact with the web, and means for controlling a rotational speed and a phase of the splice roll, with respect to the replacement roll, and a timing of urging the splice roll into contact with the web, to affix the first adhesive strip to the web downstream of the trailing edge, and to affix the second adhesive strip to the web upstream of the leading edge, with the splice sheet bridging a gap between the first and second adhesive strips, whereby first and second sides of the web are spliced to corresponding sides of the replacement web.
According to a feature of the invention, there is provided apparatus for splicing a replacement web to a web, wherein the web and the replacement web each includes first and second plies comprising: first means for splicing the first ply of the web and the replacement web together, second means for splicing the second ply of the web and the replacement web together, the second means being disposed downstream of the first means, and the first means and the second means being operable to perform the splicing while the web is in motion, whereby processing speed of the web is improved.
According to a further feature of the invention, there is provided a method for splicing a replacement web on a replacement roll to a moving web, wherein the replacement web and the web both include first and second plies, comprising: preparing a leading edge of the replacement web by trimming back an outermost portion of the second ply, which exposes an upper surface of the first ply, fixing a strip of splice tape partly below the first ply, and partly uncovered by the first ply, whereby an adhesive portion of the stirrip is exposed, preparing a web splice by affixing first and second adhesive strips spaced apart on a splice sheet, affixing, the web splice to a splice roller adjacent the moving web, with the first and second adhesive strips facing outward, accelerating the replacement roller to a peripheral speed substantially matching a speed of the moving web, urging the web against the replacement roller, and severing the moving web at a time effective for affixing the strip of splice tape to a severed trailings edge of the web, whereby the first ply of the web is spliced to the first ply of the replacement web, accelerating the splice roller to a peripheral speed substantially matching a speed of the moving web, adjusting a rotational phase of the splice roller, urging the splice roller into contact with the web at a timing which affixes the first adhesive strip downstream of the trailing edge and affixes the second adhesive strip upstream of the leading edge, with the splice sheet bridging a space between the first and second adhesive strips, whereby the second plies of the web and the replacement web are spliced to each other.
The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements.